/*
Copyright 2022 The Karmada Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package lib

import (
	"encoding/json"
	"fmt"
	"net"

	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/runtime/serializer"
	"k8s.io/apiserver/pkg/endpoints/openapi"
	"k8s.io/apiserver/pkg/registry/rest"
	genericapiserver "k8s.io/apiserver/pkg/server"
	genericoptions "k8s.io/apiserver/pkg/server/options"
	"k8s.io/apiserver/pkg/util/compatibility"
	"k8s.io/apiserver/pkg/util/feature"
	"k8s.io/klog/v2"
	"k8s.io/kube-openapi/pkg/builder"
	"k8s.io/kube-openapi/pkg/common"
	"k8s.io/kube-openapi/pkg/common/restfuladapter"
	"k8s.io/kube-openapi/pkg/validation/spec"
)

// ResourceWithNamespaceScoped contain gvr and NamespaceScoped of a resource.
type ResourceWithNamespaceScoped struct {
	GVR             schema.GroupVersionResource
	NamespaceScoped bool
}

// Config is used to configure swagger information.
type Config struct {
	Scheme             *runtime.Scheme
	Codecs             serializer.CodecFactory
	Info               spec.InfoProps
	OpenAPIDefinitions []common.GetOpenAPIDefinitions
	Resources          []ResourceWithNamespaceScoped
	Mapper             *meta.DefaultRESTMapper
}

// GetOpenAPIDefinitions get openapi definitions.
func (c *Config) GetOpenAPIDefinitions(ref common.ReferenceCallback) map[string]common.OpenAPIDefinition {
	out := map[string]common.OpenAPIDefinition{}
	for _, def := range c.OpenAPIDefinitions {
		for k, v := range def(ref) {
			out[k] = v
		}
	}
	return out
}

// RenderOpenAPISpec create openapi spec of swagger.
func RenderOpenAPISpec(cfg Config) (string, error) {
	options := genericoptions.NewRecommendedOptions("/registry/karmada.io", cfg.Codecs.LegacyCodec())
	options.SecureServing.ServerCert.CertDirectory = "/tmp/karmada-swagger"
	options.SecureServing.BindPort = 6445
	options.Etcd = nil
	options.Authentication = nil
	options.Authorization = nil
	options.CoreAPI = nil
	options.Admission = nil

	if err := options.SecureServing.MaybeDefaultWithSelfSignedCerts("localhost", nil, []net.IP{net.ParseIP("127.0.0.1")}); err != nil {
		klog.Fatal(fmt.Errorf("error creating self-signed certificates: %v", err))
	}

	serverConfig := genericapiserver.NewRecommendedConfig(cfg.Codecs)
	if err := options.SecureServing.ApplyTo(&serverConfig.Config.SecureServing, &serverConfig.Config.LoopbackClientConfig); err != nil {
		klog.Fatal(err)
		return "", err
	}
	serverConfig.OpenAPIConfig = genericapiserver.DefaultOpenAPIConfig(cfg.GetOpenAPIDefinitions, openapi.NewDefinitionNamer(cfg.Scheme))
	serverConfig.OpenAPIV3Config = genericapiserver.DefaultOpenAPIV3Config(cfg.GetOpenAPIDefinitions, openapi.NewDefinitionNamer(cfg.Scheme))
	serverConfig.OpenAPIConfig.Info.InfoProps = cfg.Info
	serverConfig.EffectiveVersion = compatibility.DefaultBuildEffectiveVersion()
	serverConfig.FeatureGate = feature.DefaultMutableFeatureGate

	genericServer, err := serverConfig.Complete().New("karmada-openapi-server", genericapiserver.NewEmptyDelegate())
	if err != nil {
		klog.Fatal(err)
		return "", err
	}

	table, err := createRouterTable(&cfg)
	if err != nil {
		klog.Fatal(err)
		return "", err
	}

	for g, resmap := range table {
		apiGroupInfo := genericapiserver.NewDefaultAPIGroupInfo(g, cfg.Scheme, metav1.ParameterCodec, cfg.Codecs)
		storage := map[string]map[string]rest.Storage{}
		for r, info := range resmap {
			if storage[info.gvk.Version] == nil {
				storage[info.gvk.Version] = map[string]rest.Storage{}
			}
			storage[info.gvk.Version][r.Resource] = &StandardREST{info}
			// Add status router for all resources.
			storage[info.gvk.Version][r.Resource+"/status"] = &StatusREST{StatusInfo{
				gvk: info.gvk,
				obj: info.obj,
			}}

			// To define additional endpoints for CRD resources, we need to
			// implement our own REST interface and add it to our custom path.
			if r.Resource == "clusters" {
				storage[info.gvk.Version][r.Resource+"/proxy"] = &ProxyREST{}
			}
		}

		for version, s := range storage {
			apiGroupInfo.VersionedResourcesStorageMap[version] = s
		}

		// Install api to apiserver.
		if err := genericServer.InstallAPIGroup(&apiGroupInfo); err != nil {
			klog.Fatal(err)
			return "", err
		}
	}

	// Create Swagger Spec.
	spec, err := builder.BuildOpenAPISpecFromRoutes(restfuladapter.AdaptWebServices(genericServer.Handler.GoRestfulContainer.RegisteredWebServices()), serverConfig.OpenAPIConfig)
	if err != nil {
		klog.Fatal(err)
		return "", err
	}
	data, err := json.MarshalIndent(spec, "", "  ")
	if err != nil {
		klog.Fatal(err)
		return "", err
	}
	return string(data), nil
}

// createRouterTable create router map for every resource.
func createRouterTable(cfg *Config) (map[string]map[schema.GroupVersionResource]ResourceInfo, error) {
	table := map[string]map[schema.GroupVersionResource]ResourceInfo{}
	// Create router map for every resource
	for _, ti := range cfg.Resources {
		var resmap map[schema.GroupVersionResource]ResourceInfo
		if m, found := table[ti.GVR.Group]; found {
			resmap = m
		} else {
			resmap = map[schema.GroupVersionResource]ResourceInfo{}
			table[ti.GVR.Group] = resmap
		}

		gvk, err := cfg.Mapper.KindFor(ti.GVR)
		if err != nil {
			klog.Fatal(err)
			return nil, err
		}
		obj, err := cfg.Scheme.New(gvk)

		if err != nil {
			klog.Fatal(err)
			return nil, err
		}

		list, err := cfg.Scheme.New(gvk.GroupVersion().WithKind(gvk.Kind + "List"))
		if err != nil {
			klog.Fatal(err)
			return nil, err
		}

		resmap[ti.GVR] = ResourceInfo{
			gvk:             gvk,
			obj:             obj,
			list:            list,
			namespaceScoped: ti.NamespaceScoped,
		}
	}

	return table, nil
}
